Tri‐Sites Element Doping with Eu─Al─F Toward Stable High‐Voltage LiCoO ₂

LiCoO₂ (LCO), as the dominating cathode material for lithium-ion batteries, still cannot satisfy the growing demand for higher energy density required by advanced consumer electronic devices. Increasing the charging cut-off voltage can significantly improve the capacity of LCO, but it would face structural and interfacial degradation at high voltages, ultimately causing severe capacity fading. Herein, a tri-sites multi-element doping strategy with Eu─Al─F is proposed for high-voltage LCO. At a cut-off voltage of 4.55 V, the modified LCO cathode exhibits an initial discharge capacity of 205 mAh g^-1 and maintains over 80% capacity retention after 250 cycles. The tri-sites co-doping strategy put forward in this study can better integrate the inhibitory effect of different doping sites on irreversible H3/H1-3 phase transitions, oxygen loss, internal stress accumulation, and planar gliding, shedding light on improving the cyclic stability of high-voltage LCO.